Human immunodeficiency virus (HIV) associated sensory neuropathies (H1V-SN) are major neurological complications of the HIV infection and despite the use of highly active antiretroviral therapy (HAART), the incidence and prevalence of this often painful complication of HIV infections remains high. HIV associated sensory neuropathies are often divided into distal symmetric polyneuropathy (DSP) due to the HIV infection per se and antiretroviral toxic neuropathy (ATM) due to the use of dideoxynucleoside (DDX) drugs. Clinically both conditions are similar and likely to have a synergistic role in the pathogenesis of HIV-SN. Currently, there are no therapies aimed at reversing or slowing the progression of these painful neuropathies that affect the quality of life of HIV/AIDS patients. In the previous cycle of this grant, we have developed in vitro models of ATN and DSP and identified a novel endogenous neuroprotective pathway that exist in the peripheral nervous system (PNS). This progress is coupled to the development of a transgenic mouse model of HIV-SN that will be useful in examining the underlying mechanisms of HIV-SN. Furthermore, we identified, erythropoietin as a potential therapeutic target for HIV-SN. In the current application we propose to continue our investigations into the cellular mechanisms of distal axonal degeneration in transgenic mice treated with DDX drugs as well as molecular mechanisms by which HIV proteins and DDX drugs cause neuronal dysfunction and axonal degeneration. We will examine the role of various mitochondrial pathways involved in neuronal dysfunction and death in mediating HIV envelope protein gp120 and DDX neurotoxicity. We will use the animal model of HIV-SN to develop biomarkers of treatment effects in HIV-SN. Finally, we will explore the therapeutic potential of neurotrophic genes regulated by hypoxia inducible factor (HIF), activators of the hsp70 pathway, and cyclophilin ligands to develop novel therapies for HIV-associated sensory neuropathies. These goals are highly relevant to the patient population we serve in the clinic as there are no effective therapies for the painful sensory neuropathy associated with HIV infection and use of DDX drugs.